[PATCHv2 27/28] firmware: Add CONFIG_BUILTIN_FIRMWARE option

[David Woodhouse]

This allows arbitrary firmware files to be included in the static kernel
where the firmware loader can find them without requiring userspace to
be alive.

Signed-off-by: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
---
 Makefile             |    2 +-
 drivers/base/Kconfig |   12 ++++++++++
 firmware/Makefile    |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+), 1 deletions(-)
 create mode 100644 firmware/Makefile

diff --git a/Makefile b/Makefile
index 20b3235..ac2ab7e 100644
--- a/Makefile
+++ b/Makefile
@@ -450,7 +450,7 @@ scripts: scripts_basic include/config/auto.conf
 
 # Objects we will link into vmlinux / subdirs we need to visit
 init-y		:= init/
-drivers-y	:= drivers/ sound/
+drivers-y	:= drivers/ sound/ firmware/
 net-y		:= net/
 libs-y		:= lib/
 core-y		:= usr/
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index d7da109..b856fe8 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -34,6 +34,18 @@ config FW_LOADER
 	  require userspace firmware loading support, but a module built outside
 	  the kernel tree does.
 
+config BUILTIN_FIRMWARE
+	string "Firmware blobs to build into the kernel binary"
+	depends on FW_LOADER
+	help
+	  This option allows firmware to be built into the kernel, for the
+	  cases where the user either cannot or doesn't want to provide it from
+	  userspace at runtime (for example, when the firmware in question is
+	  required for accessing the boot device, and the user doesn't want to
+	  use an initrd). Multiple files should be separated with spaces, and
+	  the required files should exist under the firmware/ directory in
+	  the source tree.
+
 config DEBUG_DRIVER
 	bool "Driver Core verbose debug messages"
 	depends on DEBUG_KERNEL
diff --git a/firmware/Makefile b/firmware/Makefile
new file mode 100644
index 0000000..4243c5a
--- /dev/null
+++ b/firmware/Makefile
@@ -0,0 +1,58 @@
+#
+# kbuild file for firmware/
+#
+
+firmware-y :=
+
+firmware_bins := $(subst ",,$(CONFIG_BUILTIN_FIRMWARE))
+firmware_srcs := $(patsubst %,$(obj)/%.S, $(firmware_bins))
+firmware_objs := $(patsubst %,%.o, $(firmware_bins) $(firmware-y)) 
+firmware_dirs := $(patsubst %,$(objtree)/$(obj)/%,$(dir $(firmware_objs)))
+
+quiet_cmd_mkdir = MKDIR   $@
+      cmd_mkdir = mkdir -p $@
+
+ifdef CONFIG_64BIT
+SM_WORD := .quad
+SM_ALIGN := 3
+else
+ASM_WORD := .long
+ASM_ALIGN := 2
+endif
+
+quiet_cmd_fwbin = MK_FW   $@
+      cmd_fwbin = FWNAME="$(patsubst firmware/%.S,%,$@)";		     \
+		  INCFILE="$(patsubst %.S,%,$@)";			     \
+		  FWSTR="$(subst /,_,$(subst .,_,$(patsubst 		     \
+				firmware/%.S,%,$@)))";			     \
+		  echo "/* Generated by firmware/Makefile */"		> $@;\
+		  echo "    .section .rodata"				>>$@;\
+		  echo "    .align $(ASM_ALIGN)"			>>$@;\
+		  echo "_fw_$${FWSTR}_bin:"				>>$@;\
+		  echo "    .incbin \"$$INCFILE\""			>>$@;\
+		  echo "_fw_end:"					>>$@;\
+		  echo "   .section .rodata.str,\"aMS\",@progbits,1"	>>$@;\
+		  echo "    .align $(ASM_ALIGN)"			>>$@;\
+		  echo "_fw_$${FWSTR}_name:"				>>$@;\
+		  echo "    .string \"$$FWNAME\""			>>$@;\
+		  echo "    .section .builtin_fw,\"a\",@progbits"	>>$@;\
+		  echo "    .align $(ASM_ALIGN)"			>>$@;\
+		  echo "    $(ASM_WORD) _fw_$${FWSTR}_name" 		>>$@;\
+		  echo "    $(ASM_WORD) _fw_$${FWSTR}_bin" 		>>$@;\
+		  echo "    $(ASM_WORD) _fw_end - _fw_$${FWSTR}_bin"	>>$@;
+
+$(firmware_srcs): $(obj)/%.S: $(srctree)/$(obj)/% include/config/64bit.h
+	$(call cmd,fwbin)
+
+$(firmware_dirs):
+	$(call cmd,mkdir)
+
+$(patsubst %,$(obj)/%,$(firmware_objs)): $(firmware_dirs)
+
+obj-y := $(firmware_objs) 
+
+targets := $(firmware_objs) $(patsubst $(obj)/%,%, $(firmware_srcs))
+
+# Without this, built-in.o won't be created when it's empty, and the
+# final vmlinux link will fail.
+obj-n := dummy
-- 
1.5.4.5

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